https://empyrionbuddy.com/item/ReactorCore

Check the Where to Trade tab.

You can salvage a whole reactor from a Zirax Imerat if you don't target generators.

check the F1 menu Empyriopedia, under the Commodity heading. From memory I think you can buy them from the Polaris corporations Stellaris AMP and Zero Horizons. You may need to do a small quest for them first to make them willing to do business with you

Grabber の投稿を引用：

You can salvage a whole reactor from a Zirax Imerat if you don't target generators.

The Imerat has 2 small reactors. Besides leaving generators off your turret target list you also need to stay out of the reactor rooms and salvage from the hallway. The authors have placed some boobytraps to blow the cores if you cross the threshold

The Ghyst Fusion Powerplant would be a planetside PoI that will also have reactor cores in loot crates.

Just wanted to add that some T2 explorations sites (the one with bandits and a bunch of wrecks) in the bandit stash is a small fusion reactor that can be salvaged.